Exhibit 10.1
    

    

    

    
      UNIT PURCHASE AGREEMENT
    

    
      THIS UNIT PURCHASE AGREEMENT (“Agreement”) is made as of the 8th
      day of August, 2008, by and among Opexa Therapeutics, Inc., a Texas
      corporation (the “Company”), the Affiliate Investors named on Schedule I
      hereto (each an “Affiliate Investor” and collectively the “Affiliate
      Investors”) and the Non-Affiliate Investors named on Schedule II hereto
      (each a “Non-Affiliate Investor” and collectively the “Non-Affiliate
      Investors” and, together with the Affiliate Investors, the “Investors”).
    

    
      Recitals
    

    
      A.  The Company and the Investors are executing and delivering this
      Agreement in reliance upon the exemption from securities registration
      afforded by the provisions of Regulation D (“Regulation D”), as
      promulgated by the U.S. Securities and Exchange Commission (the “SEC”)
      under the Securities Act of 1933, as amended and any other applicable
      exemption; and
    

    
      B.  The Investors wish to purchase from the Company, and the Company
      wishes to sell and issue to the Investors, upon the terms and conditions
      stated in this Agreement,  units (the “Units”) each composed of (i) one
      share (the “Shares”) of the Company’s Common Stock, par value $0.50 per
      share (together with any securities into which such shares may be
      reclassified the “Common Stock”), and (ii) one warrant to purchase one
      share of Common Stock (subject to adjustment) at an exercise price of
      $1.78 per share (subject to adjustment) in the form attached hereto as
      Exhibit A (the “Series F Warrants”); and
    

    
      C.  Contemporaneous with the execution of this Agreement, the parties
      hereto will execute and deliver a Registration Rights Agreement, in the
      form attached hereto as Exhibit B (the “Registration Rights Agreement”),
      pursuant to which the Company will agree to provide certain registration
      rights under the Securities Act of 1933, as amended, and the rules and
      regulations promulgated thereunder, and applicable state securities laws.
    

    
      In consideration of the mutual promises made herein and for other good
      and valuable consideration, the receipt and sufficiency of which are
      hereby acknowledged, the parties hereto agree as follows:
    

    
          1.  Definitions.  In addition
      to those terms defined above and elsewhere in this Agreement, for the
      purposes of this Agreement, the following terms shall have the meanings
      set forth below:
    

    
      “10-K” has the meaning set forth in Section 4.6
    

    
      “Affiliate” means, with respect to any Person, any other
      Person which directly or indirectly through one or more intermediaries
      Controls, is controlled by, or is under common control with, such Person.
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
      “Affiliate Investor” has the meaning set forth in the
      Preamble to this Agreement.
    

    
      “Business Day” means a day, other than a Saturday or
      Sunday, on which banks in New York City are open for the general
      transaction of business.
    

    
      “Closing” has the meaning set forth in Section 3.
    

    
      “Closing Date” has the meaning set forth in Section 3.
    

    
      “Company’s Knowledge” means the actual knowledge of
      the executive officers (as defined in Rule 405 under the 1933 Act) of
      the Company, after due inquiry.
    

    
      “Company Patent Applications” has the meaning set forth in
      Section 4.15
    

    
      “Confidential Information” means trade secrets,
      confidential information and know-how (including but not limited to
      ideas, formulae, compositions, processes, procedures and techniques,
      research and development information, computer program code, performance
      specifications, support documentation, drawings, specifications,
      designs, business and marketing plans, and customer and supplier lists
      and related information).
    

    
      “Control” (including the terms “controlling”, “controlled
      by” or “under common control with”) means the possession, direct or
      indirect, of the power to direct or cause the direction of the
      management and policies of a Person, whether through the ownership of
      voting securities, by contract or otherwise.
    

    
      “Effective Date” means the date on which the initial
      Registration Statement is declared effective by the SEC.
    

    
      “Effectiveness Deadline” means the date on which the
      initial Registration Statement is required to be declared effective by
      the SEC under the terms of the Registration Rights Agreement.
    

    
      “Environmental Laws” has the meaning set forth in Section
      4.16.
    

    
      “Evaluation Date” has the meaning set forth in Section 4.26.
    

    
      “GAAP” has the meaning set forth in Section 4.18.
    

    
      “Intellectual Property Rights” has the meaning set forth in
      Section 4.15.
    

    
      “Investor” has the meaning set forth in the Preamble to
      this Agreement.
    

    
      “Licenses” has the meaning set forth in Section 4.15.
    

    
      “Material Adverse Effect” means a material adverse effect
      on (i) the assets, liabilities, results of operations, condition
      (financial or otherwise), business, or prospects of the Company and its
      Subsidiaries taken as a whole, or (ii) the ability of the Company to
      perform its obligations under the Transaction Documents.
    

    
      “Non-Affiliate Investor” has the meaning set forth
      in the Preamble to this Agreement.
    

    
      
        

        

      

      
        
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      “Person” means an individual, corporation, partnership,
      limited liability company, trust, business trust, association, joint
      stock company, joint venture, sole proprietorship, unincorporated
      organization, governmental authority or any other form of entity not
      specifically listed herein.
    

    
      “Principal Market” means the Nasdaq Capital Market.
    

    
      “Prohibited Transaction” has the meaning set forth in
      Section 5.11.
    

    
      “PTO” has the meaning set forth in Section 4.15.
    

    
      “Purchase Price” means with regard to the Non-Affiliate
      Investors $1.48 for each Unit and with regard to the Affiliate Investors
      the higher of (1) the sum of (x) the Market Price (as defined in the
      Warrant) on the date of the execution of the Agreement and (y) $0.125 or
      (2) $1.48 for each Unit.
    

    
      “Registration Rights Agreement” has the meaning set forth
      in the recitals.
    

    
      “Registration Statement” has the meaning set forth in the
      Registration Rights Agreement.
    

    
      “SEC Filings” has the meaning set forth in Section 4.6.
    

    
      “Securities” means the Shares, the Series F Warrants and
      the Warrant Shares.
    

    
      “Shares” means the shares of Common Stock being purchased
      by the Investors hereunder.
    

    
      “Subsidiary” of any Person means another Person, an amount
      of the voting securities, other voting ownership or voting partnership
      interests of which is sufficient to elect at least a majority of its
      Board of Directors or other governing body (or, if there are no such
      voting interests, 50% or more of the equity interests of which) is owned
      directly or indirectly by such first Person.
    

    
      “Trading Affiliates” has the meaning set forth in Section
      5.11.
    

    
      “Transaction Documents” means this Agreement, the Series F
      Warrants, and the Registration Rights Agreement.
    

    
      “Transfer Agent” has the meaning set forth in Section 7.8.
    

    
      “Unit” has the meaning set forth in the recitals.
    

    
      “Warrants” has the meaning set forth in the recitals.
    

    
      “Warrant Shares” means the shares of Common Stock issuable
      upon the exercise of the Series F Warrants.
    

    
      “1933 Act” means the Securities Act of 1933, as amended, or
      any successor statute, and the rules and regulations promulgated
      thereunder.
    

    
      
        

        

      

      
        
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      “1934 Act” means the Securities Exchange Act of 1934, as
      amended, or any successor statute, and the rules and regulations
      promulgated thereunder.
    

    
          2.  Purchase and Issuance of the
      Units.  Subject to the terms and conditions of this Agreement, on
      the Closing Date, each of the Investors shall severally, and not
      jointly, purchase, and the Company shall sell and issue to the
      Investors, the number of Units set forth opposite the Investors’ names
      on the signature pages attached hereto in exchange for the Purchase
      Price.
    

    
          3.  Closing.
    

    
            3.1.   Upon the satisfaction or waiver of the conditions herein,
      the purchase and sale of the Units shall take place remotely via the
      exchange of documents and signatures, on or before August 8, 2008, or at
      such other time and place as the Company and the Investors mutually
      agree upon, orally or in writing (which time and place are designated as
      the “Closing”).
    

    
            3.2.  At the Closing, the Company shall deliver, or cause to be
      delivered, to each Investor (i) a certificate or certificates,
      registered in the name of the Investor, representing the Shares in the
      Units purchased by such Investor and (ii) a Series F Warrant
      representing the Series F Warrants in the Units purchased by such
      Investor, against delivery to the Company by the Investor of payment
      therefor in immediately available funds by wire transfer to an account
      designated by the Company. The Company shall also deliver such other
      documents as are called for herein.
    

    
          4.  Representations and Warranties
      of the Company.  The Company hereby represents and warrants to the
      Investors that, except as set forth in the schedules delivered herewith
      (collectively, the “Disclosure Schedules”):
    

    
            4.1.  Organization,
      Good Standing and Qualification.  The Company is a corporation duly
      organized, validly existing and in good standing under the laws of the
      jurisdiction of its incorporation and has all requisite corporate power
      and authority to carry on its business as now conducted and to own its
      properties.  The Company is duly qualified to do business as a foreign
      corporation and is in good standing in each jurisdiction in which the
      conduct of its business or its ownership or leasing of property makes
      such qualification or leasing necessary unless the failure to so qualify
      has not had and could not reasonably be expected to have a Material
      Adverse Effect.  The Company does not have any Subsidiaries.
    

    
            4.2.  Authorization.  The
      Company has full power and authority and has taken all requisite action
      on the part of the Company, its officers, directors and stockholders
      necessary for (i) the authorization, execution and delivery of the
      Transaction Documents, (ii) the authorization of the performance of all
      obligations of the Company hereunder or thereunder, and (iii) the
      authorization, issuance (or reservation for issuance) and delivery of
      the Securities.  The Transaction Documents constitute the legal, valid
      and binding obligations of the Company, enforceable against the Company
      in accordance with their terms, subject to bankruptcy, insolvency,
      fraudulent transfer, reorganization, moratorium and similar laws of
      general applicability, relating to or affecting creditors’ rights
      generally.
    

    
      
        

        

      

      
        
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            4.3.  Capitalization.  Schedule
      4.3 sets forth (a) the authorized capital stock of the Company on
      the date hereof; (b) the number of shares of capital stock issued and
      outstanding; (c) the number of shares of capital stock issuable pursuant
      to the Company’s stock plans; and (d) the number of shares of capital
      stock issuable and reserved for issuance pursuant to securities (other
      than the Shares and the Series F Warrants) exercisable for, or
      convertible into or exchangeable for any shares of capital stock of the
      Company.  All of the issued and outstanding shares of the Company’s
      capital stock have been duly authorized and validly issued and are fully
      paid, nonassessable and free of pre-emptive rights and were issued in
      full compliance with applicable state and federal securities law and any
      rights of third parties.  Except as described on Schedule
      4.3, no Person is entitled to pre-emptive or similar statutory or
      contractual rights with respect to any securities of the
      Company.  Except as described on Schedule 4.3, there
      are no outstanding warrants, options, convertible securities or other
      rights, agreements or arrangements of any character under which the
      Company is or may be obligated to issue any equity securities of any
      kind and except as contemplated by this Agreement, the Company is not
      currently in negotiations for the issuance of any equity securities of
      any kind.  Except as described on Schedule 4.3 and
      except for the Registration Rights Agreement, there are no voting
      agreements, buy-sell agreements, option or right of first purchase
      agreements or other agreements of any kind among the Company and any of
      the securityholders of the Company relating to the securities of the
      Company held by them.  Except as described on Schedule 4.3
      and except as provided in the Registration Rights Agreement, no Person
      has the right to require the Company to register any securities of the
      Company under the 1933 Act, whether on a demand basis or in connection
      with the registration of securities of the Company for its own account
      or for the account of any other Person.
    

    
      Except as described on Schedule 4.3, the issuance and sale of the
      Securities hereunder will not obligate the Company to issue shares of
      Common Stock or other securities to any other Person (other than the
      Investors) and will not result in the adjustment of the exercise,
      conversion, exchange or reset price of any outstanding security.
    

    
      Except as described on Schedule 4.3, the Company does not have
      outstanding stockholder purchase rights or “poison pill” or any similar
      arrangement in effect giving any Person the right to purchase any equity
      interest in the Company upon the occurrence of certain events.
    

    
            4.4.  Valid Issuance.  The
      Shares have been duly and validly authorized and, when issued and paid
      for pursuant to this Agreement, will be validly issued, fully paid and
      nonassessable, and shall be free and clear of all encumbrances and
      restrictions (other than those created by the Investors), except for
      restrictions on transfer set forth in the Transaction Documents or
      imposed by applicable securities laws.  The Series F Warrants have been
      duly and validly authorized.  The Company has reserved from its
      authorized Common Stock for issuance upon exercise of the Series F
      Warrants that number of shares equal to 120% of the number of Series F
      Warrants issued.  Upon the due exercise of the Series F Warrants, the
      Warrant Shares will be validly issued, fully paid and non-assessable
      free and clear of all encumbrances and restrictions, except for
      restrictions on transfer set forth in the Transaction Documents or
      imposed by applicable securities laws and except for those created by
      the Investors.  The Company has reserved a sufficient number of shares
      of Common Stock for issuance upon the exercise of the Series F Warrants,
      free and clear of all encumbrances and restrictions, except for
      restrictions on transfer set forth in the Transaction Documents or
      imposed by applicable securities laws and except for those created by
      the Investors.
    

    
      
        

        

      

      
        
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            4.5.  Consents.  The
      execution, delivery and performance by the Company of the Transaction
      Documents and the offer, issuance and sale of the Securities require no
      consent of, action by or in respect of, or filing with, any Person,
      governmental body, agency, or official other than filings that have been
      made pursuant to applicable state securities laws and post-sale filings
      pursuant to applicable state and federal securities laws which the
      Company undertakes to file within the applicable time periods.  Subject
      to the accuracy of the representations and warranties of each Investor
      set forth in Section 5 hereof, the Company has taken all action
      necessary to exempt (i) the issuance and sale of the Securities, (ii)
      the issuance of the Warrant Shares upon due exercise of the Series F
      Warrants, and (iii) the other transactions contemplated by the
      Transaction Documents from the provisions of any stockholder rights plan
      or other “poison pill” arrangement, any anti-takeover, business
      combination or control share law or statute binding on the Company or to
      which the Company or any of its assets and properties may be subject and
      any provision of the Company’s Articles of Incorporation or Bylaws that
      is or could reasonably be expected to become applicable to the Investors
      as a result of the transactions contemplated hereby, including without
      limitation, the issuance of the Securities and the ownership,
      disposition or voting of the Securities by the Investors or the exercise
      of any right granted to the Investors pursuant to this Agreement or the
      other Transaction Documents.
    

    
            4.6.  Delivery of SEC
      Filings; Business.  The Company has made available to the Investors
      through the EDGAR system, true and complete copies of the Company’s most
      recent Annual Report on Form 10-K for the fiscal year ended December 31,
      2007 (the “10-K”), and all other reports filed by the Company pursuant
      to the 1934 Act since the filing of the 10-K and prior to the date
      hereof (collectively, the “SEC Filings”).  The SEC Filings are the only
      filings required of the Company pursuant to the 1934 Act for such
      period.  The Company is engaged in all material respects only in the
      business described in the SEC Filings and the SEC Filings contain a
      complete and accurate description in all material respects of the
      business of the Company, taken as a whole.
    

    
            4.7.  Use of Proceeds.  The
      net proceeds of the sale of the Shares and the Series F Warrants
      hereunder shall be used by the Company for the completion of the
      Phase IIb clinical trial of the Company’s Tovaxin® product, including
      without limitation, the accumulation and analysis of data.  Excess
      proceeds, if any, may be used for working capital and general corporate
      purposes.
    

    
            4.8.  No Material
      Adverse Change.  Except as disclosed in Schedule 4.8,
      since March 31, 2008, there has not been:
    

    
                     (i)  any change in the consolidated assets, liabilities,
      financial condition or operating results of the Company from that
      reflected in the financial statements included in the Company’s
      Quarterly Report on Form 10-Q for the quarter ended March 31, 2008,
      except for changes in the ordinary course of business which have not had
      and could not reasonably be expected to have a Material Adverse Effect,
      individually or in the aggregate;
    

    
                    (ii)  any declaration or payment of any dividend, or any
      authorization or payment of any distribution, on any of the capital
      stock of the Company, or any redemption or repurchase of any securities
      of the Company;
    

    
      
        

        

      

      
        
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                   (iii)  any material damage, destruction or loss, whether or
      not covered by insurance to any assets or properties of the Company;
    

    
                    (iv)  any waiver, not in the ordinary course of business,
      by the Company of a material right or of a material debt owed to it;
    

    
                     (v)  any satisfaction or discharge of any lien, claim or
      encumbrance or payment of any obligation by the Company, except in the
      ordinary course of business and which is not material to the assets,
      properties, financial condition, operating results or business of the
      Company taken as a whole (as such business is presently conducted and as
      it is proposed to be conducted);
    

    
                    (vi)  any change or amendment to the Company's Articles of
      Incorporation or Bylaws, or material change to any material contract or
      arrangement by which the Company is bound or to which any of their
      respective assets or properties is subject;
    

    
                   (vii)  any material labor difficulties or labor union
      organizing activities with respect to employees of the Company;
    

    
                  (viii)  any material increases in the compensation, bonuses,
      benefits, perks or severance packages that are payable to any employee
      of the Company;
    

    
                    (ix)  any hiring of any senior management or officer level
      employee of the Company other than Neil Warma;
    

    
                     (x)  any material transaction entered into by the Company
      or a Subsidiary other than in the ordinary course of business;
    

    
                    (xi)  the loss of the services of any key employee, or
      material change in the composition or duties of the senior management of
      the Company;
    

    
                   (xii)  the loss or threatened loss of any customer which
      has had or could reasonably be expected to have a Material Adverse
      Effect; or
    

    
                  (xiii)  any other event or condition of any character that
      has had or could reasonably be expected to have a Material Adverse
      Effect.
    

    
            4.9.  SEC Filings.  At
      the time of filing thereof, the SEC Filings complied as to form in all
      material respects with the requirements of the 1934 Act and did not
      contain any untrue statement of a material fact or omit to state any
      material fact necessary in order to make the statements made therein, in
      the light of the circumstances under which they were made, not
      misleading.  Since August 1, 2006, the Company has timely filed all
      reports required to be filed by it under the 1934 Act and the rules and
      regulations promulgated thereunder.
    

    
           4.10.  No Conflict, Breach,
      Violation or Default.  The execution, delivery and performance of
      the Transaction Documents by the Company and the issuance and sale of
      the Securities will not conflict with or result in a breach or violation
      of any of the terms and provisions of, or constitute a default under (i)
      the Company’s Articles of Incorporation or the Company’s Bylaws, both as
      in effect on the date hereof (true and complete copies of which have
      been made available to the Investors through the EDGAR system), or (ii)
      any statute, rule, regulation or order of any governmental agency or
      body or any court, domestic or foreign, having jurisdiction over the
      Company or any of its assets or properties (“Governmental Authority”),
      except in the case of this clause (i) for such breaches, violations or
      defaults which would not, individually or in the aggregate, have a
      Material Adverse Effect or (iii) any agreement or instrument to which
      the Company is a party or by which the Company is bound, except in the
      case of this clause (iii) for such breaches, violations or defaults
      which would not, individually or in the aggregate, have a Material
      Adverse Effect.
    

    
      
        

        

      

      
        
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           4.11.  Tax Matters.  The
      Company has timely prepared and filed all tax returns required to have
      been filed by the Company with all appropriate governmental agencies and
      timely paid all taxes shown thereon or otherwise owed by it.  The
      charges, accruals and reserves on the books of the Company in respect of
      taxes for all fiscal periods are adequate in all material respects, and
      there are no material unpaid assessments against the Company nor, to the
      Company’s Knowledge, any basis for the assessment of any additional
      taxes, penalties or interest for any fiscal period or audits by any
      federal, state or local taxing authority except for any assessment which
      is not material to the Company, taken as a whole.  All taxes and other
      assessments and levies that the Company is required to withhold or to
      collect for payment have been duly withheld and collected and paid to
      the proper governmental entity or third party when due.  There are no
      tax liens or claims pending or, to the Company’s Knowledge, threatened
      against the Company or any of their respective assets or
      property.  There are no outstanding tax sharing agreements or other such
      arrangements between the Company and any other corporation or entity.
    

    
           4.12.  Title to Properties.  Except
      as disclosed in Schedule 4.12, the Company has good and
      marketable title to all real properties and all other properties and
      assets owned by it, in each case free from liens, encumbrances and
      defects that would materially affect the value thereof or materially
      interfere with the use made or currently planned to be made thereof by
      them or as disclosed in Schedule 4.12; and except as disclosed in Schedule
      4.12, the Company holds any leased real or personal property under
      valid and enforceable leases with no exceptions that would materially
      interfere with the use made or currently planned to be made thereof by
      it.
    

    
           4.13.  Certificates,
      Authorities and Permits.  The Company possesses adequate
      certificates, authorities or permits issued by appropriate governmental
      agencies or bodies necessary to conduct the business now operated by it,
      and the Company has not received any notice of proceedings relating to
      the revocation or modification of any such certificate, authority or
      permit that, if determined adversely to the Company or such Subsidiary,
      could reasonably be expected to have a Material Adverse Effect,
      individually or in the aggregate.
    

    
           4.14.  Labor Matters.
    

    
                 (a)  The Company is not a party to or bound by any collective
      bargaining agreements or other agreements with labor organizations.  The
      Company has not violated in any material respect any laws, regulations,
      orders or contract terms, affecting the collective bargaining rights of
      employees, labor organizations or any laws, regulations or orders
      affecting employment discrimination, equal opportunity employment, or
      employees’ health, safety, welfare, wages and hours.
    

    
      
        

        

      

      
        
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                 (b)  (i) There are no labor disputes existing, or to the
      Company's Knowledge, threatened, involving strikes, slow-downs, work
      stoppages, job actions, disputes, lockouts or any other disruptions of
      or by the Company's employees, (ii) there are no unfair labor practices
      or petitions for election pending or, to the Company's Knowledge,
      threatened before the National Labor Relations Board or any other
      federal, state or local labor commission relating to the Company's
      employees, (iii) no demand for recognition or certification heretofore
      made by any labor organization or group of employees is pending with
      respect to the Company and (iv) the Company enjoys good labor and
      employee relations with its employees and labor organizations.
    

    
                 (c)  The Company is, and at all times has been, in compliance
      in all material respects with all applicable laws respecting employment
      (including laws relating to classification of employees and independent
      contractors) and employment practices, terms and conditions of
      employment, wages and hours, and immigration and naturalization.  There
      are no claims pending against the Company before the Equal Employment
      Opportunity Commission or any other administrative body or in any court
      asserting any violation of Title VII of the Civil Rights Act of 1964,
      the Age Discrimination Act of 1967, 42 U.S.C. §§ 1981 or 1983 or any
      other federal, state or local Law, statute or ordinance barring
      discrimination in employment.
    

    
                 (d)  Except as disclosed on Schedule 4.14,
      the Company is not a party to, or bound by, any employment or other
      contract or agreement that contains any severance, termination pay or
      change of control liability or obligation, including, without
      limitation, any “excess parachute payment,” as defined in Section
      2806(b) of the Internal Revenue Code.
    

    
                 (e)  Each of the Company's employees is a Person who is
      either a United States citizen or a permanent resident entitled to work
      in the United States.  The Company has no liability for the improper
      classification by the Company of such employees as independent
      contractors or leased employees prior to the Closing.
    

    
           4.15.  Intellectual Property.
    

    
                 (a)  The Company owns or possesses the right to use
      sufficient trademarks, trade names, patent rights, copyrights, domain
      names, licenses, approvals, trade secrets, inventions, technology,
      know-how and other similar rights (collectively, “Intellectual Property
      Rights”) as are necessary or material to conduct its business as now
      conducted and as described in the Company’s Form 10-K  for the year
      ending December 31, 2007 (the “2007 10-K”) or in the Company’s Quarterly
      Report on Form 10-Q for the quarter ended March 31, 2008.  Except as set
      forth in Schedule 4.15 (a) there is no pending or, to the
      Company’s Knowledge, threatened action, suit, proceeding, or claim by
      others challenging the rights of the Company in or to any such
      Intellectual Property Rights that, if decided adversely to the Company
      would, individually or in the aggregate, have a Material Adverse Effect,
      and the Company is unaware of any facts which would form a reasonable
      basis for any such claim; (b) there is no pending, or to the Company’s
      Knowledge, threatened action, suit, proceeding, or claim by others that
      the Company infringes, misappropriates, or otherwise violates any
      Intellectual Property Rights, of others that, if decided adversely to
      the Company would, individually or in the aggregate, have a Material
      Adverse Effect, and the Company is unaware of any facts which would form
      a reasonable basis for any such claim; (c) there is no pending or, to
      the Company’s Knowledge, threatened action, suit, proceeding, or claim
      by others challenging the validity, scope, or enforceability of any such
      Intellectual Property Rights owned by the Company and the Company is
      unaware of any facts which would form a reasonable basis for any such
      claim; (d) there is no prior art of which the Company is aware that may
      render any patent owned or licensed by the Company invalid or any patent
      application owned or licensed by the Company unpatentable which has not
      been disclosed to the applicable government patent office; and (e) the
      Company’s granted or issued patents, registered trademarks, and
      registered copyrights have been duly maintained and are in full force
      and in effect, and none of the patents, trademarks and copyrights have
      been adjudged invalid or unenforceable in whole or in part.  The Company
      is not a party to or bound by any options, licenses or agreements with
      respect to the Intellectual Property Rights of any other person or
      entity that are required to be disclosed in the SEC Filings and are not
      described therein in all material respects.  None of the technology or
      intellectual property used by the Company in its business has been
      obtained or is being used by the Company in violation of any contractual
      obligation binding on the Company, or, to the Company’s Knowledge, any
      of its officers, directors, or employees or otherwise in violation of
      the rights of any persons. Each employee has executed an agreement with
      the Company assigning to it any inventions made in the performance of
      their duties.
    

    
      
        

        

      

      
        
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                 (b)  The Company has duly and properly filed or caused to be
      filed with the U.S. Patent and Trademark Office (the “PTO”) and
      applicable foreign and international patent authorities all patent
      applications owned by the Company (the “Company Patent
      Applications”).  The Company has complied with the PTO’s duty of candor
      and disclosure for the Company Patent Applications and has made no
      material misrepresentation in the Company Patent Applications.  To the
      Company’s Knowledge the Company Patent Applications disclose patentable
      subject matters. The Company has not been notified of any inventorship
      challenges nor has any interference been declared or provoked nor is any
      material fact known by the Company that would preclude the issuance of
      patents with respect to the Company Patent Applications or would render
      such patents, if issued, invalid or unenforceable.
    

    
                 (c)  The Company is not currently in breach of any provision
      of any license, contract or other agreement governing the use by the
      Company of Intellectual Property Rights owned by third parties
      (collectively, the “Licenses”) and, except as described in Schedule
      4.15, no third party has alleged any such breach and the Company is
      unaware of any facts that would form a reasonable basis for such a
      claim.  To the Company’s Knowledge, no other party to the Licenses has
      breached or is currently in breach of any provision of the
      Licenses.  Each of the Licenses is in full force and effect and
      constitutes a valid and binding agreement between the parties thereto,
      enforceable in accordance with its terms, and there has not occurred any
      breach or default under any such Licenses or any event that with the
      giving of notice or lapse of time would constitute a breach or default
      thereunder.  Except as would not have a Material Adverse Effect, the
      Company has not been and is not currently involved in any disputes
      regarding the Licenses.  To the Company’s Knowledge, all patents
      licensed to the Company pursuant to the Licenses are valid, enforceable
      and being duly maintained. All patent applications licensed to the
      Company pursuant to the Licenses are being duly prosecuted.
    

    
      
        

        

      

      
        
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           4.16.  Environmental Matters.  The
      Company (i) is not in violation of any statute, rule, regulation,
      decision or order of any governmental agency or body or any court,
      domestic or foreign, relating to the use, disposal or release of
      hazardous or toxic substances or relating to the protection or
      restoration of the environment or human exposure to hazardous or toxic
      substances (collectively, “Environmental Laws”), (ii) owns or operates
      any real property contaminated with any substance that is subject to any
      Environmental Laws, (iii) is not liable for any off-site disposal or
      contamination pursuant to any Environmental Laws, or (iv) is not subject
      to any claim relating to any Environmental Laws, which violation,
      contamination, liability or claim has had or could reasonably be
      expected to have a Material Adverse Effect, individually or in the
      aggregate; and there is no pending or, to the Company’s Knowledge,
      threatened investigation that might lead to such a claim.
    

    
           4.17.  Litigation.  There
      are no pending actions, suits or proceedings against or affecting the
      Company or any of its or their properties; and to the Company’s
      Knowledge, no such actions, suits or proceedings are threatened or
      contemplated.  The Company is not a party to or subject to the
      provisions of any order, writ, injunction, judgment, or decree of or by
      any court, or judge, justice or magistrate, including any bankruptcy
      court or judge, or any order of or by any governmental authority.  There
      are no pending actions, suits or proceedings against the Company before
      NASDAQ.
    

    
           4.18.  Financial Statements.  The
      financial statements included in each SEC Filing present fairly, in all
      material respects, the consolidated financial position of the Company as
      of the dates shown and its consolidated results of operations and cash
      flows for the periods shown, and such financial statements have been
      prepared in conformity with United States generally accepted accounting
      principles applied on a consistent basis (“GAAP”) (except as may be
      disclosed therein or in the notes thereto, and, in the case of quarterly
      financial statements, as permitted by Form 10-Q under the 1934
      Act).  Except as set forth in the financial statements of the Company
      included in the SEC Filings filed prior to the date hereof or as
      described on Schedule 4.18, the Company has not incurred any
      liabilities, contingent or otherwise, except those incurred in the
      ordinary course of business, consistent (as to amount and nature) with
      past practices since the date of such financial statements, none of
      which, individually or in the aggregate, have had or could reasonably be
      expected to have a Material Adverse Effect.
    

    
           4.19.  Insurance Coverage.  The
      Company maintains in full force and effect insurance coverage that its
      Board of Directors has determined is reasonable for the business being
      conducted and properties owned or leased by the Company, and the Company
      reasonably believes such insurance coverage to be adequate against all
      liabilities, claims and risks against which it is customary for
      comparably situated companies to insure.
    

    
           4.20.  Brokers and Finders.  No
      Person will have, as a result of the transactions contemplated by the
      Transaction Documents, any valid right, interest or claim against or
      upon the Company or an Investor for any commission, fee or other
      compensation pursuant to any agreement, arrangement or understanding
      entered into by or on behalf of the Company.
    

    
           4.21.  No Directed Selling
      Efforts or General Solicitation.  Neither the Company nor any Person
      acting on its behalf has conducted any general solicitation or general
      advertising (as those terms are used in Regulation D) in connection with
      the offer or sale of any of the Securities.
    

    
      
        

        

      

      
        
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           4.22.  No Integrated Offering.  Neither
      the Company nor any of its Affiliates, nor any Person acting on its or
      their behalf has, directly or indirectly, made any offers or sales of
      any Company security or solicited any offers to buy any security, under
      circumstances that would adversely affect reliance by the Company on
      Section 4(2) for the exemption from registration for the transactions
      contemplated hereby or would require registration of the Securities
      under the 1933 Act.
    

    
           4.23.  Private Placement.  The
      offer and sale of the Securities to the Investors as contemplated hereby
      is exempt from the registration requirements of the 1933 Act.
    

    
           4.24.  Questionable Payments.  Neither
      the Company nor its directors, officers or employees nor, to the
      Company’s Knowledge, any of its current or former stockholders, agents
      or other Persons acting on behalf of the Company, has on behalf of the
      Company or in connection with its respective businesses: (a) used any
      corporate funds for unlawful contributions, gifts, entertainment or
      other unlawful expenses relating to political activity; (b) made any
      direct or indirect unlawful payments to any governmental officials or
      employees from corporate funds; (c) established or maintained any
      unlawful or unrecorded fund of corporate monies or other assets; (d)
      made any false or fictitious entries on the books and records of the
      Company; or (e) made any unlawful bribe, rebate, payoff, influence
      payment, kickback or other unlawful payment of any nature.
    

    
           4.25.  Transactions with
      Affiliates.  Except as disclosed in Schedule 4.25,
      none of the officers or directors of the Company and none of the
      employees of the Company is presently a party to any transaction with
      the Company (other than as holders of stock options and/or warrants, and
      for services as employees, officers and directors), including any
      contract, agreement or other arrangement providing for the furnishing of
      services to or by, providing for rental of real or personal property to
      or from, or otherwise requiring payments to or from any officer,
      director or such employee or, to the Company’s Knowledge, any entity in
      which any officer, director, or any such employee has a substantial
      interest or is an officer, director, trustee or partner.
    

    
           4.26.  Internal Controls.  The
      Company is in material compliance with the provisions of the
      Sarbanes-Oxley Act of 2002 currently applicable to the Company.  The
      Company maintain a system of internal accounting controls sufficient to
      provide reasonable assurance that (i) transactions are executed in
      accordance with management's general or specific authorizations, (ii)
      transactions are recorded as necessary to permit preparation of
      financial statements in conformity with GAAP and to maintain asset
      accountability, (iii) access to assets is permitted only in accordance
      with management's general or specific authorization, and (iv) the
      recorded accountability for assets is compared with the existing assets
      at reasonable intervals and appropriate action is taken with respect to
      any differences. The Company has established disclosure controls and
      procedures (as defined in 1934 Act Rules 13a-14 and 15d-14) for the
      Company and designed such disclosure controls and procedures to ensure
      that material information relating to the Company is made known to the
      certifying officers by others within those entities, particularly during
      the period in which the Company’s most recently filed period report
      under the 1934 Act, as the case may be, is being prepared.  The
      Company's certifying officers have evaluated the effectiveness of the
      Company's controls and procedures as of the end of the period covered by
      the most recently filed periodic report under the 1934 Act (such date,
      the "Evaluation Date").  The Company presented in its most recently
      filed periodic report under the 1934 Act the conclusions of the
      certifying officers about the effectiveness of the disclosure controls
      and procedures based on their evaluations as of the Evaluation
      Date.  Since the Evaluation Date, there have been no significant changes
      in the Company's internal controls (as such term is defined in Item 308
      of Regulation S-K) or, to the Company's Knowledge, in other factors that
      could significantly affect the Company's internal controls.  The Company
      maintains and will continue to maintain a standard system of accounting
      established and administered in accordance with GAAP and the applicable
      requirements of the 1934 Act.
    

    
      
        

        

      

      
        
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           4.27.  Access to Trial Data.  As
      of the date of this Agreement, the Company’s employees, officers and
      directors have not been provided nor had an opportunity to review the
      data analysis provided to the Company’s Data and Safety Monitoring Board
      (“DSMB”) as part of their Descriptive Analysis conducted on February 22,
      2008.  The Tovaxin Phase IIb Clinical Trial for multiple sclerosis
      (“TERMS”) mid-study descriptive analysis (“Descriptive Analysis”) is an
      analysis of the safety data from TERMS collected after 50% of the
      subjects (75 subjects) completed 6 months on study.  The data provided
      to the DSMB for use in the preparation of its report were pooled and,
      additionally, no inferential statistics were computed or displayed in
      the data summaries presented in the Descriptive Analysis report.
    

    
           4.28.  Principal Market.  The
      Company is not in violation of the listing requirements of the Principal
      Market and to the Company’s Knowledge there are no facts that would
      reasonably lead to delisting or suspension of the Common Stock in the
      foreseeable future except that the Company’s stockholder equity is
      expected to decrease significantly in the absence of additional sales of
      securities and may then cause the Company to fail to meet the Principal
      Market’s continued listing requirements.  The issuance by the Company of
      the Securities shall not have the effect of delisting or suspending the
      Common Stock from the Principal Market.
    

    
           4.29.  Conduct of Business.  The
      Company is not in violation of any term of or in default under its
      Certificate of Incorporation or Bylaws.  The Company is not in violation
      of any judgment, decree or order or any statute, ordinance, rule or
      regulation applicable to the Company, and the Company will not conduct
      its business in violation of any of the foregoing, except for possible
      violations which could not, individually or in the aggregate, reasonably
      be expected to have a Material Adverse Effect.    
    

    
           4.30.  Investment Company
      Status.  The Company is not, and upon consummation of the sale of
      the Securities will not be, an "investment company," a company
      controlled by an "investment company" or an "affiliated person" of, or
      "promoter" or "principal underwriter" for, an "investment company" as
      such terms are defined in the Investment Company Act of  1940, as
      amended.
    

    
           4.31.  U.S. Real Property
      Holding Corporation.  The Company is not, has never been, and so
      long as any Securities remain outstanding, shall not become, a U.S. real
      property holding corporation within the meaning of Section 897 of the
      Internal Revenue Code of 1986, as amended, and the Company shall so
      certify upon any Investor's request.
    

    
      
        

        

      

      
        
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           4.32.  Off Balance Sheet
      Arrangements.  There is no transaction, arrangement, or other
      relationship between the Company and an unconsolidated or other off
      balance sheet entity that is required to be disclosed by the Company in
      its 1934 Act filings and is not so disclosed or that otherwise would be
      reasonably likely to have a Material Adverse Effect.  
    

    
           4.33.  Insolvency.  The
      Company has not taken any steps to seek protection pursuant to any
      bankruptcy law nor, to the Company’s Knowledge, do any of its creditors
      intend to initiate involuntary bankruptcy proceedings; and, to the
      Company’s Knowledge, there is not any fact which would reasonably lead a
      creditor to do so.  The Company is not as of the date hereof, and after
      giving effect to the transactions contemplated hereby to occur at the
      Closing, will not be Insolvent (as defined below).  For purposes of this
      Section 4.33, "Insolvent" means, with respect to any Person, (i) the
      present fair saleable value of such Person's assets is less than the
      amount required to pay such Person's total indebtedness, (ii) such
      Person is unable to pay its debts and liabilities, subordinated,
      contingent or otherwise, as such debts and liabilities become absolute
      and matured, (iii) such Person intends to incur or believes that it will
      incur debts that would be beyond its ability to pay as such debts mature
      or (iv) such Person has unreasonably small capital with which to conduct
      the business in which it is engaged as such business is now conducted.
    

    
           4.34.  Transfer Taxes.  On
      the Closing Date, all stock transfer or other taxes (other than income
      or similar taxes) which are required to be paid in connection with the
      sale and transfer of the Securities to be sold to each Investor
      hereunder will be, or will have been, fully paid or provided for by the
      Company, and all laws imposing such taxes will be or will have been
      complied with.
    

    
           4.35.  Manipulation of Price.  The
      Company has not, and to the Company’s Knowledge no one acting on its
      behalf has, (i) taken, directly or indirectly, any action designed to
      cause or to result in the stabilization or manipulation of the price of
      any security of the Company to facilitate the sale or resale of any of
      the Securities, (ii) sold, bid for, purchased, or paid any compensation
      for soliciting purchases of, any of the Securities, or (iii) paid or
      agreed to pay to any person any compensation for soliciting another to
      purchase any other securities of the Company.
    

    
           4.36.  Shell Company Status.  The
      Company has not, since the adoption of Rule 144(i) under the 1933 Act,
      been an issuer subject to such rule.
    

    
           4.37.  Employee Benefit Plans.  The
      Company and any “employee benefit plan” (as defined under the Employee
      Retirement Income Security Act of 1974, as amended, and the regulations
      and published interpretations thereunder (collectively, “ERISA”))
      established or maintained by the Company, or its “ERISA Affiliates” (as
      defined below) are in compliance in all material respects with
      ERISA.  “ERISA Affiliates” means, with respect to the Company, any
      member of any group of organizations described in
      Sections 414(b),(c),(m) or (o) of the Internal Revenue Code of 1986, as
      amended, and the regulations and published interpretations thereunder
      (the “Code”) of which the Company is a member.  No “reportable event”
      (as defined under ERISA) has occurred or is reasonably expected to occur
      with respect to any “employee benefit plan” established or maintained by
      the Company, or any of its ERISA Affiliates.  No “employee benefit plan”
      established or maintained by the Company or any of its ERISA Affiliates,
      if such “employee benefit plan” were terminated, would have any “amount
      of unfunded benefit liabilities” (as defined under ERISA).  Neither the
      Company, nor any of its ERISA Affiliates has incurred or reasonably
      expects to incur any liability under (i) Title IV of ERISA with respect
      to termination of, or withdrawal from, any “employee benefit plan” or
      (ii) Sections 412, 4971, 4975 or 4980B of the Code.  Each “employee
      benefit plan” established or maintained by the Company or any of its
      ERISA Affiliates that is intended to be qualified under Section 401(a)
      of the Code is so qualified and nothing has occurred, whether by action
      or failure to act, which would cause the loss of such qualification.
    

    
      
        

        

      

      
        
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           4.38.  Disclosure.  The
      Company confirms that neither it nor any other Person acting on its
      behalf has provided any of the Investors or their agents or counsel with
      any information that constitutes or could reasonably be expected to
      constitute material, nonpublic information.  The Company understands and
      confirms that each of the Investors will rely on the foregoing
      representations in effecting transactions in securities of the
      Company.  All disclosure provided to the Investors regarding the
      Company, its business and the transactions contemplated hereby,
      including the SEC Filings and the disclosure schedules to this
      Agreement, furnished by or on behalf of the Company, as a whole, is true
      and correct and does not contain any untrue statement of a material fact
      or omit to state any material fact necessary in order to make the
      statements made therein, in the light of the circumstances under which
      they were made, not misleading.  No event or circumstance has occurred
      or information exists with respect to the Company or its business,
      properties, prospects, operations or financial conditions, which, under
      applicable law, rule or regulation, requires public disclosure or
      announcement by the Company but which has not been so publicly announced
      or disclosed.  The Company acknowledges and agrees that no Investor
      makes or has made any representations or warranties with respect to the
      transactions contemplated hereby other than those specifically set forth
      in Section 5.
    

    
          5.  Representations and Warranties
      of the Investors.  Each of the Investors hereby severally, and not
      jointly, represents and warrants to the Company that:
    

    
            5.1.  Organization and
      Existence.  Such Investor is either an individual or a validly
      existing corporation, limited partnership or limited liability company
      and has all requisite corporate, partnership or limited liability
      company power and authority to invest in the Securities pursuant to this
      Agreement.
    

    
            5.2.  Authorization.  The
      execution, delivery and performance by such Investor of the Transaction
      Documents to which such Investor is a party have been duly authorized
      and will each constitute the valid and legally binding obligation of
      such Investor, enforceable against such Investor in accordance with
      their respective terms, subject to bankruptcy, insolvency, fraudulent
      transfer, reorganization, moratorium and similar laws of general
      applicability, relating to or affecting creditors’ rights generally.
    

    
            5.3.  Purchase Entirely
      for Own Account.  The Securities to be received by such Investor
      hereunder will be acquired for such Investor’s own account, not as
      nominee or agent, and not with a view to the resale or distribution of
      any part thereof in violation of the 1933 Act, and such Investor has no
      present intention of selling, granting any participation in, or
      otherwise distributing the same in violation of the 1933 Act without
      prejudice, however, to such Investor’s right at all times to sell or
      otherwise dispose of all or any part of such Securities in compliance
      with applicable federal and state securities laws.  Nothing contained
      herein shall be deemed a representation or warranty by such Investor to
      hold the Securities for any period of time.  Such Investor is not a
      broker-dealer registered with the SEC under the 1934 Act or an entity
      engaged in a business that would require it to be so registered.
    

    
      
        

        

      

      
        
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            5.4.  Investment
      Experience.  Such Investor acknowledges that it can bear the
      economic risk and complete loss of its investment in the Securities and
      has such knowledge and experience in financial or business matters that
      it is capable of evaluating the merits and risks of the investment
      contemplated hereby.
    

    
            5.5.  Disclosure of
      Information.  Such Investor has had an opportunity to receive all
      information related to the Company requested by it and to ask questions
      of and receive answers from the Company regarding the Company, its
      business and the terms and conditions of the offering of the
      Securities.  Such Investor acknowledges receipt of copies of the SEC
      Filings.  Neither such inquiries nor any other due diligence
      investigation conducted by such Investor shall modify, amend or affect
      such Investor’s right to rely on the Company’s representations and
      warranties contained in this Agreement.
    

    
            5.6.  Restricted
      Securities.  Such Investor understands that the Securities are
      characterized as “restricted securities” under the U.S. federal
      securities laws inasmuch as they are being acquired from the Company in
      a transaction not involving a public offering and that under such laws
      and applicable regulations such securities may be resold without
      registration under the 1933 Act only in certain limited circumstances.
    

    
            5.7.  Legends.  It
      is understood that, except as provided below, certificates evidencing
      the Securities may bear the following or any similar legend:
    

    
                 (a)  “The securities represented hereby may not be
      transferred unless (i) such securities have been registered for sale
      pursuant to the Securities Act of 1933, as amended, (ii) such securities
      may be sold pursuant to Rule 144, or (iii) the Company has received an
      opinion of counsel reasonably satisfactory to it that such transfer may
      lawfully be made without registration under the Securities Act of 1933
      or qualification under applicable state securities laws.”
    

    
                 (b)  If required by the authorities of any state in
      connection with the issuance of sale of the Securities, the legend
      required by such state authority.
    

    
            5.8.  Accredited
      Investor.  Such Investor is an accredited investor as defined in
      Rule 501(a) of Regulation D, as amended, under the 1933 Act.
    

    
            5.9.  No General
      Advertisement.  Such Investor did not learn of the investment in the
      Securities as a result of any public advertisement, article, notice or
      other communication regarding the Securities published in any newspaper,
      magazine or similar media or broadcast over television, radio or
      internet or presented at any seminar or other general advertisement.
    

    
           5.10.  Brokers and Finders.  No
      Person will have, as a result of the transactions contemplated by the
      Transaction Documents, any valid right, interest or claim against or
      upon the Company or an Investor for any commission, fee or other
      compensation pursuant to any agreement, arrangement or understanding
      entered into by or on behalf of such Investor.
    

    
      
        

        

      

      
        
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           5.11.  Prohibited Transactions.  During
      the last thirty (30) days prior to the date hereof, neither such
      Investor nor any Affiliate of such Investor which (x) had knowledge of
      the transactions contemplated hereby, (y) has or shares discretion
      relating to such Investor’s investments or trading or information
      concerning such Investor’s investments, including in respect of the
      Securities, or (z) is subject to such Investor’s review or input
      concerning such Affiliate’s investments or trading (collectively,
      “Trading Affiliates”) has, directly or indirectly, effected or agreed to
      effect any short sale, whether or not against the box, established any
      “put equivalent position” (as defined in Rule 16a-1(h) under the 1934
      Act) with respect to the Common Stock, granted any other right
      (including, without limitation, any put or call option) with respect to
      the Common Stock or with respect to any security that includes, relates
      to or derived any significant part of its value from the Common Stock or
      otherwise sought to hedge its position in the Securities (each, a
      “Prohibited Transaction”).  Notwithstanding the foregoing, for the
      avoidance of doubt, shares of Common Stock held by an Investor on or
      prior to the date hereof may be sold after the public announcement of
      the sale of the Units without such sale constituting a "Prohibited
      Transaction." Prior to the earliest to occur of (i) the termination of
      this Agreement, (ii) the Effective Date or (iii) the Effectiveness
      Deadline, such Investor shall not, and shall cause its Trading
      Affiliates not to, engage, directly or indirectly, in a Prohibited
      Transaction.  Such Investor acknowledges that the representations,
      warranties and covenants contained in this Section 5.11 are being made
      for the benefit of the Investors as well as the Company and that each of
      the other Investors shall have an independent right to assert any claims
      against such Investor arising out of any breach or violation of the
      provisions of this Section 5.11.
    

    
          6.  Conditions to Closing.
    

    
            6.1.  Conditions to the
      Investors’ Obligations. The obligation of each Investor to
      purchase the Shares and the Series F Warrants at the Closing is subject
      to the fulfillment to such Investor’s satisfaction, on or prior to the
      Closing Date, of the following conditions, any of which may be waived by
      such Investor (as to itself only):
    

    
                 (a)  The representations and warranties made by the Company
      in Section 4 hereof qualified as to materiality shall be true and
      correct at all times prior to and on the Closing Date, except to the
      extent any such representation or warranty expressly speaks as of an
      earlier date, in which case such representation or warranty shall be
      true and correct as of such earlier date, and, the representations and
      warranties made by the Company in Section 4 hereof not qualified as to
      materiality shall be true and correct in all material respects.  The
      Company shall have performed in all material respects all obligations
      and covenants herein required to be performed by them on or prior to the
      Closing Date.
    

    
                 (b)  The Company shall have obtained any and all consents,
      permits, approvals, registrations and waivers necessary or appropriate
      for consummation of the purchase and sale of the Securities and the
      consummation of the other transactions contemplated by the Transaction
      Documents, all of which shall be in full force and effect.
    

    
      
        

        

      

      
        
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                 (c)  The Company shall have delivered or caused the delivery
      to each Investor a stock certificate for the Shares the Investor is
      purchasing hereunder and an original Series F Warrant for the Series F
      Warrants the Investor is purchasing hereunder.
    

    
                 (d)  The Company shall have executed and delivered the
      Registration Rights Agreement.
    

    
                 (e)  The Company shall have received executed Purchase
      Agreements for the sale of Units that will result in gross proceeds of
      at least Two Million Dollars ($2,000,000) and not more than Three
      Million Five Thousand Dollars ($3,005,000).
    

    
                 (f)  No judgment, writ, order, injunction, award or decree of
      or by any court, or judge, justice or magistrate, including any
      bankruptcy court or judge, or any order of or by any governmental
      authority, shall have been issued, and no action or proceeding shall
      have been instituted by any governmental authority, enjoining or
      preventing the consummation of the transactions contemplated hereby or
      in the other Transaction Documents.
    

    
                 (g)  The Company shall have delivered a Certificate, executed
      on behalf of the Company by its Chief Executive Officer or its Chief
      Financial Officer, dated as of the Closing Date, certifying to the
      fulfillment of the conditions specified in subsections (a), (b), (e),
      (f) and (i) of this Section 6.1.
    

    
                 (h)  The Company shall have delivered a Certificate, executed
      on behalf of the Company by its Secretary, dated as of the Closing Date,
      certifying the resolutions adopted by the Board of Directors of the
      Company approving the transactions contemplated by this Agreement and
      the other Transaction Documents and the issuance of the Securities,
      certifying the current versions of the Articles of Incorporation and
      Bylaws of the Company and certifying as to the signatures and authority
      of persons signing the Transaction Documents and related documents on
      behalf of the Company.
    

    
                 (i)  No stop order or suspension of trading shall have been
      imposed by the SEC or any other governmental or regulatory body with
      respect to public trading in the Common Stock.
    

    
                 (j)  The Company shall have delivered a certificate from the
      Texas Secretary of State certifying to its existence and a certificate
      of good standing from the Texas Comptroller.
    

    
                 (k)  The Company shall have requested and caused Vinson &
      Elkins L.L.P., counsel for the Company, to furnish to the Investors its
      opinion, dated the Closing Date and addressed to the Initial Purchasers,
      substantially in the form attached hereto as Exhibit C.
    

    
            6.2.  Conditions to
      Obligations of the Company.  The Company's obligation to sell and
      issue the Shares and the Series F Warrants at the Closing is subject to
      the fulfillment to the satisfaction of the Company on or prior to the
      Closing Date of the following conditions, any of which may be waived by
      the Company:
    

    
      
        

        

      

      
        
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                 (a)  The representations and warranties made by the Investors
      in Section 5 hereof (the “Investor Representations”) qualified as to
      materiality shall be true and correct at all times prior to and on the
      Closing Date, except to the extent any such representation or warranty
      expressly speaks as of an earlier date, in which case such
      representation or warranty shall be true and correct as of such earlier
      date, and, the Investor Representations made by the Investors in Section
      5 hereof not qualified as to materiality shall be true and correct in
      all material respects.  The Investors shall have performed in all
      material respects all obligations and covenants herein required to be
      performed by it on or prior to the Closing Date.
    

    
                 (b)  The Investors shall have executed and delivered the
      Registration Rights Agreement.
    

    
                 (c)  The Investors shall have delivered the Purchase Price to
      the Company.
    

    
            6.3.  Termination of
      Obligations to Effect Closing; Effects.
    

    
                 (a)  The obligations of the Company, on the one hand, and the
      Investors, on the other hand, to effect the Closing shall terminate as
      follows:
    

    
                     (i)  Upon the mutual written consent of the Company and
      the Investors;
    

    
                    (ii)  By the Company if any of the conditions set forth in
      Section 6.2 shall have become incapable of fulfillment, and shall not
      have been waived by the Company;
    

    
                   (iii)  By an Investor (with respect to itself only) if any
      of the conditions set forth in Section 6.1 shall have become incapable
      of fulfillment, and shall not have been waived by the Investor; or
    

    
                    (iv)  By either the Company or any Investor (with respect
      to itself only) if the Closing has not occurred on or prior to 5:00
      p.m., Houston time, on August 15, 2008;
    

    
      provided, however, that, except in the case of clause (i) above, the
      party seeking to terminate its obligation to effect the Closing shall
      not then be in breach of any of its representations, warranties,
      covenants or agreements contained in this Agreement or the other
      Transaction Documents if such breach has resulted in the circumstances
      giving rise to such party’s seeking to terminate its obligation to
      effect the Closing.
    

    
                 (b)  In the event of termination by the Company or any
      Investor of its obligations to effect the Closing pursuant to this
      Section 6.3, written notice thereof shall forthwith be given to the
      other Investors and the other Investors shall have the right to
      terminate their obligations to effect the Closing upon written notice to
      the Company and the other Investors.  Nothing in this Section 6.3 shall
      be deemed to release any party from any liability for any breach by such
      party of the terms and provisions of this Agreement or the other
      Transaction Documents or to impair the right of any party to compel
      specific performance by any other party of its obligations under this
      Agreement or the other Transaction Documents.
    

    
      
        

        

      

      
        
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          7.  Covenants and Agreements of the
      Company.
    

    
            7.1.  Reservation of
      Common Stock.  So long as any Investor owns any Series F Warrants,
      the Company shall take all action necessary to at all times have
      authorized, and reserved for the purpose of issuance, no less than 120%
      of the sum of the number of shares of Common Stock issuable upon
      exercise of the Series F Warrants then outstanding (without taking into
      account any limitations on exercise of the Series F Warrants set forth
      in the Series F Warrants).  If at any time the authorized and reserved
      shares are not sufficient to satisfy the foregoing requirement, the
      Company will promptly take all corporate action necessary to authorize
      and reserve a sufficient number of shares, including, without
      limitation, calling a special meeting of stockholders to authorize
      additional shares to meet the Company’s obligations under this Section
      7.1.
    

    
            7.2.  Reports.  The
      Company will furnish to the Investors and/or their assignees such
      information relating to the Company and any Subsidiaries as from time to
      time may reasonably be requested by the Investors and/or their
      assignees; provided, however, that the Company shall not disclose
      material nonpublic information to the Investors, or to advisors to or
      representatives of the Investors, unless prior to disclosure of such
      information the Company identifies such information as being material
      nonpublic information and provides the Investors, such advisors and
      representatives with the opportunity to accept or refuse to accept such
      material nonpublic information for review and any Investor wishing to
      obtain such information enters into an appropriate confidentiality
      agreement with the Company with respect thereto.
    

    
            7.3.  No Conflicting
      Agreements.  The Company will not take any action, enter into any
      agreement or make any commitment that would conflict or interfere in any
      material respect with the Company’s obligations to the Investors under
      the Transaction Documents.
    

    
            7.4.  Insurance.  The
      Company shall maintain in full force and effect insurance coverage that
      is customary for comparably situated companies for the business being
      conducted and properties owned or leased by the Company and any
      Subsidiary, in amounts the Company reasonably believes to be adequate
      against all liabilities, claims and risks against which it is customary
      for comparably situated companies to insure.
    

    
            7.5.  Compliance with
      Laws.  The Company will comply in all material respects with all
      applicable laws, rules, regulations, orders and decrees of all
      governmental authorities.
    

    
            7.6.  Listing of
      Underlying Shares and Related Matters.  Promptly following the
      Closing, the Company shall take all necessary action to cause the Shares
      and the Warrant Shares to be listed on the Nasdaq Capital Market as soon
      as practicable after the Closing Date.  Further, if the Company applies
      to have its Common Stock or other securities traded on any other
      principal stock exchange or market, it shall include in such application
      the Shares and the Warrant Shares and will take such other action as is
      necessary to cause such Common Stock to be so listed.  Once approved for
      listing, the Company will use its best efforts to continue the listing
      and trading of its Common Stock on the Nasdaq Capital Market and, in
      accordance, therewith, will use its best efforts to comply in all
      respects with the Company’s reporting, filing and other obligations
      under the bylaws or rules of such market or exchange, as applicable.
    

    
      
        

        

      

      
        
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            7.7.  Termination of
      Covenants.  The provisions of Sections 7.2, 7.4 and 7.5 shall
      terminate and be of no further force and effect on the date on which all
      of the Warrants cease to be outstanding.
    

    
            7.8.  Removal of Legends.  (a) Upon
      the earlier of (i) registration for resale pursuant to the Registration
      Rights Agreement or (ii) Rule 144 becoming available to the applicable
      Investor with respect to the resale of such applicable Securities then
      held by such Investor, the Company shall (A) deliver to the transfer
      agent for the Common Stock (the “Transfer Agent”) irrevocable
      instructions that the Transfer Agent shall reissue a certificate
      representing shares of Common Stock without legends upon receipt by such
      Transfer Agent of the legended certificates for such shares, together
      with either (1) a customary representation by the Investor that Rule 144
      applies to the shares of Common Stock represented thereby or (2) a
      statement by the Investor that such Investor has sold the shares of
      Common Stock represented thereby in accordance with the Plan of
      Distribution contained in the Registration Statement and, if applicable,
      in accordance with any prospectus delivery requirements, and (B) cause
      its counsel to deliver to the Transfer Agent one or more blanket
      opinions to the effect that the removal of such legends in such
      circumstances may be effected under the 1933 Act.  From and after the
      earlier of such dates, upon an Investor’s written request, the Company
      shall promptly cause certificates evidencing the Investor’s Securities
      to be replaced with certificates which do not bear such restrictive
      legends, and Warrant Shares subsequently issued upon due exercise of the
      Series F Warrants shall not bear such restrictive legends provided the
      provisions of either clause (i) or clause (ii) above, as applicable, are
      satisfied with respect to such Warrant Shares.
    

    
                 (b)  Additional
      Relief.  If the Company shall fail for any reason or for no reason
      to issue to the Investor unlegended certificates or issue such Common
      Shares to such Investor by electronic delivery at the applicable balance
      account at DTC within three (3) Trading Days after the receipt of
      documents necessary for the removal of the legend set forth in Section
      5.7 above (the “Removal Date”), then in addition to all other remedies
      available to the Investor, if on or after the Trading Day immediately
      following such three Trading Day period, the Investor purchases (in an
      open market transaction or otherwise) shares of Common Stock to deliver
      in satisfaction of a sale by the Investor of such Common Shares that the
      Investor anticipated receiving without legend from the Company (a
      "Buy-In"), then the Company shall, within three (3) Business Days after
      the Investor’s request and in the Investor’s discretion, either (i) pay
      cash to the Investor in an amount equal to the Investor’s total purchase
      price (including brokerage commissions, if any) for the shares of Common
      Stock so purchased (the "Buy-In Price"), at which point the Company's
      obligation to deliver such unlegended Common Shares shall terminate, or
      (ii) promptly honor its obligation to deliver to the Investor such
      unlegended Common Shares as provided above and pay cash to the Investor
      in an amount equal to the excess (if any) of the Buy-In Price over the
      product of (A) such number of shares of Common Stock, times (B) the
      Market Price (as defined in the Warrants) on the Removal Date.
    

    
      
        

        

      

      
        
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            7.9.  Disclosure of
      Transactions and Other Material Information.  On or before 8:30
      a.m., New York City time, on the fourth Business Day following the
      Closing Date, the Company shall issue a press release and file a Current
      Report on Form 8-K describing the terms of the transactions contemplated
      by the Transaction Documents in the form required by the 1934 Act and
      attaching the material Transaction Documents (including, without
      limitation, this Agreement, the form of Series F Warrant and the form of
      the Registration Rights Agreement as exhibits to such filing (including
      all attachments, the "8 K Filing").  From and after the filing of the
      8-K Filing with the SEC, no Investor shall be in possession of any
      material, nonpublic information received from the Company, any of its
      Subsidiaries or any of their respective officers, directors, employees
      or agents, that is not disclosed in the 8-K Filing.  The Company shall
      not, and shall cause each of its officers, directors, employees and
      agents, not to, provide any Investor with any material, nonpublic
      information regarding the Company or any Subsidiaries from and after the
      filing of the 8-K Filing with the SEC without the express written
      consent of such Investor.  Subject to the foregoing, the Company shall
      not issue any press releases or any other public statements with respect
      to the transactions contemplated hereby; provided, however, that the
      Company shall be entitled, without the prior approval of any Investor,
      to make any press release or other public disclosure with respect to
      such transactions (i) in substantial conformity with the 8-K Filing and
      (ii) as is otherwise required by applicable law and regulations
      (provided that in the case of clause (i) Charles Sheedy and Diker
      Management, LLC shall be consulted by the Company in connection with any
      such press release or other public disclosure prior to its
      release).  Except as required in the Registration Statement, without the
      prior written consent of any applicable Investor, neither the Company
      nor any of its affiliates shall disclose the name of such Investor in
      any filing, announcement, release or otherwise.
    

    
           7.10.  Integrated Offering.  None
      of the Company, its affiliates and any Person acting on their behalf
      will take any action or steps referred to in Section 4.22 that would
      require registration of any of the Securities under the 1933 Act.
    

    
           7.11.  Variable Securities.  For
      so long as any Warrants remain outstanding, the Company shall not, in
      any manner, issue or sell any rights, warrants or options to subscribe
      for or purchase Common Stock or directly or indirectly convertible into
      or exchangeable or exercisable for Common Stock at a price which varies
      or may vary with the market price of the Common Stock, including by way
      of one or more reset(s) to any fixed price unless the conversion,
      exchange or exercise price of any such security cannot be less than the
      then Exercise Price (as defined in the Warrants) with respect to the
      Common Stock into which any Warrant is exercisable.  
    

    
           7.12.  Public Information.  At
      any time during the period commencing from the six (6) month anniversary
      of the Closing Date and ending at such time that all of the Securities,
      may be sold without restriction or limitation pursuant to Rule 144 and
      without the requirement to be in compliance with Rule 144(c)(1), and provided
      that no registration statement is available for the resale of all of the
      Securities during such period, if the Company shall fail for any reason
      to satisfy the current public information requirement under Rule 144(c)
      (a "Public Information Failure") then, as partial relief for the damages
      to any holder of Securities by reason of any such delay in or reduction
      of its ability to sell the Securities (which remedy shall not be
      exclusive of any other remedies available at law or in equity), the
      Company shall pay to each such holder an amount in cash equal to one and
      one-half percent (1.5%) of the aggregate Purchase Price of such holder's
      Securities on the day of a Public Information Failure and on every
      thirtieth day (pro rated for periods totaling less than thirty days)
      thereafter until the earlier of (i) the date such Public Information
      Failure is cured and (ii) such time that such public information is no
      longer required pursuant to Rule 144.  The payments to which a holder
      shall be entitled pursuant to this Section 7.12 are referred to herein
      as "Public Information Failure Payments."  Public Information Failure
      Payments shall be paid on the earlier of (I) the last day of the
      calendar month during which such Public Information Failure Payments
      are incurred and (II) the third Business Day after the event or failure
      giving rise to the Public Information Failure Payments is
      cured.  In the event the Company fails to make Public Information Failure
      Payments in a timely manner, such Public Information Failure Payments
      shall bear interest at the rate of 1.5% per month (prorated for partial
      months) until paid in full.
    

    
      
        

        

      

      
        
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          8.  Survival and Indemnification.
    

    
            8.1.  Survival.  The
      representations, warranties, covenants and agreements contained in this
      Agreement shall survive the Closing of the transactions contemplated by
      this Agreement.
    

    
            8.2.  Indemnification.  The
      Company agrees to indemnify and hold harmless each Investor and its
      Affiliates and their respective directors, officers, employees, agents,
      successors and permitted assigns from and against any and all losses,
      claims, damages, liabilities and expenses (including without limitation
      reasonable attorney fees and disbursements and other expenses incurred
      in connection with investigating, preparing or defending any action,
      claim or proceeding, pending or threatened and the costs of enforcement
      thereof) (collectively, “Losses”) to which such Person may become
      subject as a result of any breach of representation, warranty, covenant
      or agreement made by or to be performed on the part of the Company under
      the Transaction Documents, and will reimburse any such Person for all
      such amounts as they are incurred by such Person.
    

    
            8.3.  Conduct of
      Indemnification Proceedings.  Promptly after receipt by any Person
      (the “Indemnified Person”) of notice of any demand, claim or
      circumstances which would or might give rise to a claim or the
      commencement of any action, proceeding or investigation in respect of
      which indemnity may be sought pursuant to Section 8.2, such Indemnified
      Person shall promptly notify the Company in writing and the Company
      shall assume the defense thereof, including the employment of counsel
      reasonably satisfactory to such Indemnified Person, and shall assume the
      payment of all fees and expenses; provided, however, that the failure of
      any Indemnified Person so to notify the Company shall not relieve the
      Company of its obligations hereunder except to the extent that the
      Company is materially prejudiced by such failure to notify.  In any such
      proceeding, any Indemnified Person shall have the right to retain its
      own counsel, but the fees and expenses of such counsel shall be at the
      expense of such Indemnified Person unless: (i) the Company and the
      Indemnified Person shall have mutually agreed to the retention of such
      counsel; or (ii) in the reasonable judgment of counsel to such
      Indemnified Person representation of both parties by the same counsel
      would be inappropriate due to actual or potential differing interests
      between them.  The Company shall not be liable for any settlement of any
      proceeding effected without its written consent, which consent shall not
      be unreasonably withheld, but if settled with such consent, or if there
      be a final judgment for the plaintiff, the Company shall indemnify and
      hold harmless such Indemnified Person from and against any loss or
      liability (to the extent stated above) by reason of such settlement or
      judgment.  Without the prior written consent of the Indemnified Person,
      which consent shall not be unreasonably withheld, the Company shall not
      effect any settlement of any pending or threatened proceeding in respect
      of which any Indemnified Person is or could have been a party and
      indemnity could have been sought hereunder by such Indemnified Party,
      unless such settlement includes an unconditional release of such
      Indemnified Person from all liability arising out of such proceeding.
    

    
      
        

        

      

      
        
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          9.  Miscellaneous.
    

    
            9.1.  Successors and
      Assigns.  This Agreement may not be assigned by a party hereto
      without the prior written consent of the Company or the Investors, as
      applicable, provided, however, that an Investor may assign its rights
      and delegate its duties hereunder in whole or in part to an Affiliate or
      to a third party acquiring some or all of its Securities in a private
      transaction without the prior written consent of the Company or the
      other Investors, after notice duly given by such Investor to the Company
      provided, that no such assignment or obligation shall affect the
      obligations of such Investor hereunder.  The provisions of this
      Agreement shall inure to the benefit of and be binding upon the
      respective permitted successors and assigns of the parties.  Nothing in
      this Agreement, express or implied, is intended to confer upon any party
      other than the parties hereto or their respective successors and assigns
      any rights, remedies, obligations, or liabilities under or by reason of
      this Agreement, except as expressly provided in this Agreement.
    

    
            9.2.  Counterparts;
      Faxes.  This Agreement may be executed in two or more counterparts,
      each of which shall be deemed an original, but all of which together
      shall constitute one and the same instrument.  This Agreement may also
      be executed via facsimile, which shall be deemed an original.
    

    
            9.3.  Titles and
      Subtitles.  The titles and subtitles used in this Agreement are used
      for convenience only and are not to be considered in construing or
      interpreting this Agreement.
    

    
            9.4.  Notices.  Unless
      otherwise provided, any notice required or permitted under this
      Agreement shall be given in writing and shall be deemed effectively
      given as hereinafter described (i) if given by personal delivery, then
      such notice shall be deemed given upon such delivery, (ii) if given by
      telex or telecopier, then such notice shall be deemed given upon receipt
      of confirmation of complete transmittal, (iii) if given by mail, then
      such notice shall be deemed given upon the earlier of (A) receipt of
      such notice by the recipient or (B) three days after such notice is
      deposited in first class mail, postage prepaid, and (iv) if given by an
      internationally recognized overnight air courier, then such notice shall
      be deemed given one Business Day after delivery to such carrier.  All
      notices shall be addressed to the party to be notified at the address as
      follows, or at such other address as such party may designate by ten
      days’ advance written notice to the other party:
    

    
      
        

        

      

      
        
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      If to the Company:
    

    
      Opexa Therapeutics, Inc.
2635 Crescent Ridge Drive
The Woodlands,
      Texas 77381
Attention:  Lynne Hohlfeld
Facsimile:  (281)
      872-8585
    

    
      With a copy to:
    

    
      Vinson & Elkins, LLP
1001 Fannin, Suite 2500
Houston, Texas
      77002
Attention:  Michael C. Blaney
Facsimile:  (713)
      758-3487
    

    
      If to the Investors:
    

    
      to the addresses set forth on the signature pages hereto.
    

    
            9.5.  Expenses.  The
      parties hereto shall pay their own costs and expenses in connection
      herewith, except that the Company shall pay the reasonable fees and
      expenses of Boyar & Miller not to exceed $15,000 and of Schulte, Roth &
      Label not to exceed $20,000.  In the event that legal proceedings are
      commenced by any party to this Agreement against another party to this
      Agreement in connection with this Agreement or the other Transaction
      Documents, the party or parties which do not prevail in such proceedings
      shall severally, but not jointly, pay their pro rata share (based on the
      relative number of Units purchased hereunder) of the reasonable
      attorneys’ fees and other reasonable out-of-pocket costs and expenses
      incurred by the prevailing party in such proceedings.  It is
      acknowledged that Boyar & Miller solely represented Charles Sheedy and
      David Jordon in connection with this Agreement and the other Transaction
      Documents and no other party, including any other Investor.
    

    
            9.6.  Amendments and
      Waivers.  Any term of this Agreement may be amended and the
      observance of any term of this Agreement may be waived (either generally
      or in a particular instance and either retroactively or prospectively),
      only with the written consent of the Company and the Investors.  Any
      amendment or waiver effected in accordance with this paragraph shall be
      binding upon each holder of any Securities purchased under this
      Agreement at the time outstanding, each future holder of all such
      Securities, and the Company.
    

    
            9.7.  Publicity.  Except
      as set forth below, no public release or announcement concerning the
      transactions contemplated hereby shall be issued by the Company or the
      Investors without the prior consent of the Company (in the case of a
      release or announcement by the Investors) or Charles Sheedy and Diker
      Management, LLC (in the case of a release or announcement by the
      Company) (which consents shall not be unreasonably withheld), except as
      such release or announcement may be required by law or the applicable
      rules or regulations of any securities exchange or securities market, in
      which case the Company or the Investors, as the case may be, shall allow
      the Investors or the Company, as applicable, to the extent reasonably
      practicable in the circumstances, reasonable time to comment on such
      release or announcement in advance of such issuance.  In addition, the
      Company will make such other filings and notices in the manner and time
      required by the SEC.  Notwithstanding the foregoing, the Company shall
      not publicly disclose the name of any Investor, or include the name of
      any Investor in any filing with the SEC (other than the Registration
      Statement and any exhibits to filings made in respect of this
      transaction in accordance with periodic filing requirements under the
      1934 Act) or any regulatory agency, without the prior written consent of
      such Investor, except to the extent such disclosure is required by law
      or trading market regulations, in which case the Company shall provide
      the Investors with prior notice of such disclosure.
    

    
      
        

        

      

      
        
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            9.8.  Severability.  Any
      provision of this Agreement that is prohibited or unenforceable in any
      jurisdiction shall, as to such jurisdiction, be ineffective to the
      extent of such prohibition or unenforceability without invalidating the
      remaining provisions hereof but shall be interpreted as if it were
      written so as to be enforceable to the maximum extent permitted by
      applicable law, and any such prohibition or unenforceability in any
      jurisdiction shall not invalidate or render unenforceable such provision
      in any other jurisdiction.  To the extent permitted by applicable law,
      the parties hereby waive any provision of law which renders any
      provision hereof prohibited or unenforceable in any respect.
    

    
            9.9.  Entire Agreement.  This
      Agreement, including the Exhibits and the Disclosure Schedules, and the
      other Transaction Documents constitute the entire agreement among the
      parties hereof with respect to the subject matter hereof and thereof and
      supersede all prior agreements and understandings, both oral and
      written, between the parties with respect to the subject matter hereof
      and thereof.
    

    
           9.10.  Further Assurances.  The
      parties shall execute and deliver all such further instruments and
      documents and take all such other actions as may reasonably be required
      to carry out the transactions contemplated hereby and to evidence the
      fulfillment of the agreements herein contained.
    

    
           9.11.  Governing Law; Consent
      to Jurisdiction; Waiver of Jury Trial.  This Agreement shall be
      governed by, and construed in accordance with, the internal laws of the
      State of Texas without regard to the choice of law principles
      thereof.  Each of the parties hereto irrevocably submits to the
      exclusive jurisdiction of the courts of the State of Texas located in
      Harris County and the United States District Court for the Southern
      District of Texas and the courts of the State of New York located in the
      City of New York, Borough of Manhattan, and the United States District
      Court for the Southern District of New York for the purpose of any suit,
      action, proceeding or judgment relating to or arising out of this
      Agreement and the transactions contemplated hereby.  Service of process
      in connection with any such suit, action or proceeding may be served on
      each party hereto anywhere in the world by the same methods as are
      specified for the giving of notices under this Agreement.  Each of the
      parties hereto irrevocably consents to the jurisdiction of any such
      court in any such suit, action or proceeding and to the laying of venue
      in such court.  Each party hereto irrevocably waives any objection to
      the laying of venue of any such suit, action or proceeding brought in
      such courts and irrevocably waives any claim that any such suit, action
      or proceeding brought in any such court has been brought in an
      inconvenient forum.  EACH OF THE PARTIES HERETO WAIVES ANY
      RIGHT TO REQUEST A TRIAL BY JURY IN ANY LITIGATION WITH RESPECT TO THIS
      AGREEMENT AND REPRESENTS THAT COUNSEL HAS BEEN CONSULTED SPECIFICALLY AS
      TO THIS WAIVER.
    

    
      
        

        

      

      
        
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           9.12.  Independent Nature of
      Investors' Obligations and Rights.  The obligations of each Investor
      under any Transaction Document are several and not joint with the
      obligations of any other Investor, and no Investor shall be responsible
      in any way for the performance of the obligations of any other Investor
      under any Transaction Document.  The decision of each Investor to
      purchase Securities pursuant to the Transaction Documents has been made
      by such Investor independently of any other Investor.  Nothing contained
      herein or in any Transaction Document, and no action taken by any
      Investor pursuant thereto, shall be deemed to constitute the Investors
      as a partnership, an association, a joint venture or any other kind of
      entity, or create a presumption that the Investors are in any way acting
      in concert or as a group with respect to such obligations or the
      transactions contemplated by the Transaction Documents.  Each Investor
      acknowledges that no other Investor has acted as agent for such Investor
      in connection with making its investment hereunder and that no Investor
      will be acting as agent of such Investor in connection with monitoring
      its investment in the Securities or enforcing its rights under the
      Transaction Documents.  Each Investor shall be entitled to independently
      protect and enforce its rights, including, without limitation, the
      rights arising out of this Agreement or out of the other Transaction
      Documents, and it shall not be necessary for any other Investor to be
      joined as an additional party in any proceeding for such purpose.  The
      Company acknowledges that each of the Investors has been provided with
      the same Transaction Documents for the purpose of closing a transaction
      with multiple Investors and not because it was required or requested to
      do so by any Investor.
    

    
      [signature page follows]
    

    
      
        

        

      

      
        
          27
        

        
          


        

      

      
        

        

      

    

    
      IN WITNESS WHEREOF, the parties have executed this Agreement or caused
      their duly authorized officers to execute this Agreement as of the date
      first above written.
    

    
    	
          The Company:
        	
          
            OPEXA THERAPEUTICS, INC.
          

        
	

        	
          
            By: /s/ Neil K. Warma
          

        
	

        	
          Neil K. Warma
        
	

        	
          President and Chief Executive Officer
        


    

    
      


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Albert and Margaret Alkek Foundation
          

        
	

        	
          
            By: /s/ Scott B. Seaman
          

        
	

        	
          
            Name: Scott B. Seaman
          

        
	

        	
          
            Title: Executive Director
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⊠           
    

    
    	
          Aggregate Purchase Price: $ 225,000.00
        	

        
	
          Number of Units: 135,951
        	

        
	
          
             
          

        	

        
	

        	
           
        
	

        	
           
        
	
          
            Address for Notice:
          

        	
           
        
	

        	
           
        
	
          
             
          

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Alkek & Williams Ventures, Ltd.
          

        
	

        	
          
            By: /s/ Scott B. Seaman
          

        
	

        	
          
            Name: Scott B. Seaman
          

        
	

        	
          
            Title: Attorney-in-Fact
          

        


    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $           87,500.00
    

    
      Number of Units:                       52,870
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Diker M&S Cap Master, Ltd.
          

        
	

        	
          
            By: /s/ Mark Diker
          

        
	

        	
          
            Name: Mark Diker
          

        
	

        	
          
            Title: Managing Partner
          

        


    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:      ⊠
    

    
      Aggregate Purchase Price:  $        112,000.00
    

    
      Number of Units:                       75,675
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Diker Micro and Small Cap Fund, LP
          

        
	

        	
          
            By: /s/ Mark Diker
          

        
	

        	
          
            Name: Mark Diker
          

        
	

        	
          
            Title: Managing Partner
          

        


    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⊠
    

    
      Aggregate Purchase Price:  $        112,000.00
    

    
      Number of Units:                       75,676
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Diker Micro-Value QP Fund, LP
          

        
	

        	
          
            By: /s/ Mark Diker
          

        
	

        	
          
            Name: Mark Diker
          

        
	

        	
          
            Title: Managing Partner
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:     ⊠
    

    
      Aggregate Purchase Price:  $        259,000.00
    

    
      Number of Units:                       175,000
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Diker Micro-Value Fund, LP
          

        
	

        	
          
            By: /s/ Mark Diker
          

        
	

        	
          
            Name: Mark Diker
          

        
	

        	
          
            Title: Managing Partner
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⊠
    

    
      Aggregate Purchase Price:  $        217,000.00
    

    
      Number of Units:                       146,622
    

    

    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            DLD Family Investments, LLC
          

        
	

        	
          
            By: /s/ Laura Liang
          

        
	

        	
          
            Name: Laura Liang
          

        
	

        	
          
            Title: Vice President
          

        


    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $        87,500.00
    

    
      Number of Units:                       59,121
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            David Hung
          

        
	

        	
          
            By: /s/ David Hung
          

        
	

        	
          
            Name: David Hung
          

        
	

        	
          
            Title:
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $  25,000.00
    

    
      Number of Units:                 15,105                
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            David E. Jorden
          

        
	

        	
          
            By: /s/ David E. Jorden
          

        
	

        	
          
            Name: David E. Jorden
          

        
	

        	
          Title:
        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $    125,060.00
    

    
      Number of Units:                   84,500
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            David E. Jorden Rollover IRA
          

        
	

        	
          
            By: /s/ David E. Jorden
          

        
	

        	
          
            Name: David E. Jorden
          

        
	

        	
          Title:
        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $        274,540.00
    

    
      Number of Units:                       185,500
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            LB I Group Inc.
          

        
	

        	
          
            By: /s/ Jeffrey Ferrell
          

        
	

        	
          
            Name: Jeffrey Ferrell
          

        
	

        	
          
            Title: Sr. Vice President
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⊠
    

    
      Aggregate Purchase Price:  $        999,999.00
    

    
      Number of Units:                       675,675
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Scott B. Seaman
          

        
	

        	
          
            By: /s/ Scott B. Seaman
          

        
	

        	
          
            Name: Scott B. Seaman
          

        
	

        	
          Title:
        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $        25,000.00
    

    
      Number of Units:                       15,105
    

    

    

    
    	
          Address for Notice:
        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Charles E. Sheedy
          

        
	

        	
          
            By: /s/ Charles E. Sheedy
          

        
	

        	
          
            Name: Charles E. Sheedy
          

        
	

        	
          Title:
        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:    ⃞
    

    
      Aggregate Purchase Price:  $        450,000.00
    

    
      Number of Units:                       304,054
    

    
    	
          Address for Notice:
        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
    	
          The Investors:
        	
          
            Neil K. Warma
          

        
	

        	
          
            By: /s/ Neil K. Warma
          

        
	

        	
          
            Name: Neil K. Warma
          

        
	

        	
          
            Title: President & CEO
          

        


    

    

    

    
      Optional Provisions:
    

    
      Unless checked here Section 3(d) of the Warrant will not be included in
      your Warrant:     ⃞
    

    
      Aggregate Purchase Price:  $                            5,000.00
    

    
      Number of Units:                                           3,021
    

    
    	
          Address for Notice:
        	
           
        
	

        	
           
        
	

        	
           
        
	

        	
          Attention:
        
	

        	
          Facsimile:
        
	

        	
          Email:
        


    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
      EXHIBIT A
    

    
      Form of Series F Warrant
    

    
      (to be attached)
    

    

    

    

    

    
      Exhibit A
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
      EXHIBIT B
    

    
      Form of Registration Rights Agreement
    

    
      (to be attached)
    

    

    

    

    

    
      Exhibit B
to Unit Purchase Agreement
    

    
      
        

        

      

      
        

        

        
          


        

      

      
        

        

      

    

    
      EXHIBIT C
    

    
      Form of Legal Opinion of Vinson & Elkins LLP
    

    
      (to be attached)
    

    

    

    

    

    
      Exhibit C
to Unit Purchase Agreement